Default Which of these SD card files can I safely delete?

My SD card is really cluttered and I'd like to clean it up.

.estrongs
.face
.SPenSDK30
.Spensound
Android
backups
CameraZOOM
clockworkmod
data
data-app
DCIM
doubleTwist
Download
KingsoftOffice
media
Movies
Music
Nandroid_Manager
Nearby
onandroid
pers
Photo Grid
Pictures
Playlists
Ringtones
roidapp
Samsung
tapatalk4
Tasker
TempImages
TitaniumBackup
WhatsApp
Yahoo!
.aid.bak
.bugsense
.enref
.eu.chainfire.mobileodin.flashkernel.n9005.v5
.profig.os
busybox-stericson
log.txt
toolbox-stericson
Xposed-Disabler-Recovery.zip

Particularly, I'm looking at the files, not folders. The folders are pretty self-explanatory, but what about files like .aid.bak and .enref? Can they be safely deleted?